Strong and plastic metallic composites with nanolayered architectures
ZH Cao and W Sun and YJ Ma and Q Li and Z Fan and YP Cai and ZJ Zhang and H Wang and X Zhang and XK Meng, ACTA MATERIALIA, 195, 240-251 (2020).
Nanostructured metals and alloys are generally strong but lack strain hardening due to enhanced grain boundary diffusion and sliding. Here, equal nanograined (ENG) and gradient nanograined (GNG) layered Cu/Ta architectures were acquired by introducing a hard and stable "artificial" interphase boundary zone (IBZ). The ENG architecture produced uniform plastic strain reaching 70% and high yield strength exceeding 1 GPa, which is attributed to the constraint effect of the tough IBZ on dislocation slip mediated co-deformation. The GNG architecture exhibited a remarkable linear strain hardening with hardening exponent of 1 due to the strong strain partitioning between soft and hard layers. The dominant deformation mechanism of the GNG nanocomposite evolves from partial dislocation emission to dislocation accumulation at interface with increasing strain based on the results from experiments and molecular dynamics simulations. This finding demonstrates that heterostructure with "artificial" IBZ may offer an alternative approach to design strong and tough materials. (C) 2020 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.
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